CPK level in psychiatric patient

Recently we had a psychiatric patient that was transferred to us due to high creatinin phosphokinase (CPK) level in the blood stream. Generally CPK level is higher in psychiotic patient due to the medications that they are taking. There are various studies published in the 70's about the effect of typical anti-psychotic (neuroleptic) drugs on CPK level. Namely it causes a benign rise in CPK level that can often be confused with underlying pathology. However, in certain instances, the rise in CPK level can be due to pathological process.

In patient that's taking neuroleptic, we're worried about neuroleptic malignant syndrome (NMS) which is characterized by muscle rigidity, fever (>106F), and cognitive changes such as delirium. Mainstay of treatment for this syndrome is to discontinue the medication (classic anti-psychotic) and supportive care. The msucle rigidity causes rhabdomyolysis and thus high CPK level. In instances when the patient has severely elevated CPK level (>15000) or underlying renal problems or risk factors for renal damage, the patient will receive intra-venous fluid (IVF) to help clear out CPK and preserve renal function. This is done because CPK is mainly cleared from the body by the kidneys and high levels of it will kill the kidney. This brings us to why the patient previously mentioned wind up in our care.

The patient was transferred to us because of elevated CPK level and the psych ward decided the patient needed IVF to protect the patient's renal function. However, the patient has no predisposing factors nor prior renal pathology. In addition, the patient's CPK level was high, but not THAT high (~6000.)

In a study published on exertional rhabdomyolysis, healthy patient can reach level as high as 10,000 without any symptoms. Other more recent case report on elevated CPK and psych patient showed two cases where level of around 10,000 was treated with oral fluid and did fine clinically without any sequelae (future pathological process associated with this instance.)

In managing the patient, the CPK serum level should be drawn to monitor progress. Generally, the patient's CPK serum level should decrease by 40% each day provided that all insults were removed and patient is resting. The most dramatic decrease should be within the first 6 to 8 hours.

In summary:

-admit patient if

-CPK >15,000 (if otherwise healthy)

-has predisposing renal risk (sickle cell, PCKD, transplanted kidney)

-has renal failure

-the patient is a lawyer